Support test group comparisons

[vishnuchalla]

Description

As hunter has this feature of having tests divided into groups and then compare between them for regressions, I think it would be nice to get it integrated in this tool.

Acceptance Criteria

• Orion should be able to accept a config file that has tests divided into groups and feed it to hunter to spit out the comparison results between each group regression results.
• As a user, I would want to compare between regression results. For example OCP 4.15 vs OCP 4.16 over a period of time and see those how trends are correlated with each other.

[qiliRedHat]

Some new discussion about this in slack: https://redhat-internal.slack.com/archives/C05CDC19ZKJ/p1718281521457749, so I opened https://github.com/cloud-bulldozer/orion/issues/42. But found it is a dup to this one.